Currently the detection of fetal magnetocardiogram (fMCG) is not possible at gestational ages earlier than 15 weeks, is unreliable at gestations less than 20-24 weeks, and is often difficult in obese patients even in the last trimester. This presents a series problem in the assessment of fetal heart conditions in patients with high- risk cardiac conditions in specific, and in prenatal care management in general. Transvaginal approach for fetal echocardiography has enhanced fetal imaging by allowing better resolution of extremely small fetal anatomy at close range down to about 13 weeks, but cannot precisely measure fetal heart rhythm and conduction disorders. To answer this challenge, pioneering work on fMCG has demonstrated the unique capabilities of SQUID-based fetal MCG system, including QRS and QT interval measurements, accurate beat- to-beat analysis, precise arrhythmia recording, and detailed fetal heart rate trend analysis. The objective of proposal is to develop a transvaginal SQUID fMCG system for direct recording of fetal cardiac activities at gestational ages younger 15 weeks, and in addition fetal brain electromagnetic activity. This will facilitate early detections of intrauterine clinical condition of fetuses with life-threatening arrhythmias, acquired heart failure, and structural congenital heart disease. Unlike the conventional fetal MCG system, which is bulky and requires to be installed in a heavy and costly magnetic shielded room, the new system will be designed to be compact and light, suitable for use in clinical settings. In this Phase II work we have identified major technical challenges, and will address them systematically to pave way for smooth transition to human testing in Phase III and to future clinical operations. The Phase I instrument will be modified to incorporate vector measurement and noise cancellation channels. The animal tests will be conducted to demonstrate the feasibility of the improved Phase I instrument in live objects. In data analysis new noise reduction algorithm will be integrated and tested. Results of these studies will guide the design and construction of light weight magnetic shielding that is easily adaptive to OBGYN clinics; vector sensor probe with reference array that can accommodate development of fetus at different pregnancy stages; safe and comfortable patient chair and probe gantry to streamline test procedures. A series of tests will be carried out to access risk level in simulated mechanical and cryogenic failures of the probe. Successful completion of this program will lead to the first-ever diagnostic tool for fetal cardiology that is capable of providing accurate recording from early pregnancy stages. It offers the significant ability to identify fetal arrhythmias and other cardiac disorders. In addition, it will greatly advance scientific knowledge on both fetal heart and brain development, which can lead to better prenatal care and potential treatments for genetic disorders. 1